Circular data

The special nature of circular data means that conventional methods suitable for the analysis of linear data do not apply. In this article, we survey a range of methods that have been developed over the last 50 years to handle the special characteristics of data consisting of angular measurements. We discuss summary statistics and graphical methods, methods for the analysis of single and multiple samples of circular data, circular correlation, regression methods, and time series. We discuss the standard probability models on which these analyses are based, and give several examples of the application of these methods. A reasonably comprehensive bibliography is provided. (C) 2010 John Wiley & Sons, Inc.